owens, abc news, mexico city. >>> and something truly unexpected today, a powerful, high-profile man came forward, a senator, revealing that he was sexually abused as a child, hoping to help other victims. massachusetts senator scott brown making it clear it's a painful memory 40 years later. john berman told us what he said. >> reporter: it was the handsome truck-driving former model who shocked the world with his victory in massachusetts. now, a new shock from scott brown, revealing for the first time that he was a victim of sexual abuse. >> he said, "if you tell anybody, i'll kill you. i will make sure that nobody believes you." >> reporter: in an interview with "60 minutes" about his new book, "against all odds," the 51-year-old senator says it happened at summer camp in fourth grade. >> when people find people like me, at that young, vulnerable age who are, basically, lost, the thing that they have over you is they make you believe that no one will believe you. >> reporter: it was part of a harrowing childhood for brown. he told barbara walters about repeated physical abuse. >> it was with my mom's husband. a couple of husbands. you know, having to be the man of the family and come and rescue her and getting knocke